Why are mosquitoes and bedbugs successful?

surajt88

Hi all. Mosquitoes and bed bugs that dint give us an itch after being bitten would have had an enormous advantage over normal mosquitoes and bed bugs as we wouldnt notice or bother if we dint feel anything. By natural selection, these types of bugs would have had an edge over current bugs. I've come to know that the itching sensation is due to the compounds the bugs inject to prevent blood clot while they suck. So, why dont we have irritation-less mosquitoes and bed bugs? Is it because there isnt a compound that both doesnt irritate us and prevents blood clot or hasn't there been enough time for them to evolve?

Pythagorean

Many states jokingly call mosquitos their state bird. In my state, they come in such vast hordes that plenty of them get away, full of enough blood to spread progeny. For a sufficiently small crowd of mosquitos, many of us (not me, personally, I hate the bastards) just adapt to ignoring them. They also get us while we're sleeping.

Also, humans are extremely hygienic and picky, and have very exposed skin compared to most mammals; mammals like bulvines can also do little about mosquitos compared to humans. We aren't their only prey.

Evolution can be lazy to selection pressures. It doesn't have to perform at 110% if it's getting by with 10%. It's not a graduate student : )

tiny-tim

because we are!

surajt88

So the reason must be that its cheaper for mosquitoes to be as they are as we are not the only ones in their diet!

Pythagorean

One might argue that it's not a cheaper solution; just there's not enough evolutionary pressure to "push the ball over the hump" so it can "settle into the lower state". As long as it's in a surviving state, it doesn't have to always be the cheapest state.

Monique

Your statement that there would be an enormous advantage is not correct, the mosquitoes are already successful in getting an animal's blood. At the point it starts itching the mosquito is already far underway in getting its meal.

surajt88

We normally use mosquito repellents and other means to kill them most often because their bite irritates us. If we did not feel anything, why kill them (unless in malaria prone areas)? So it seems to me that it is an advantage for them to go unnoticed.

Monique

That is a very anthropocentric point of view. One can place mosquito nets in a house or locally spray DEET, but then the mosquito can easily find another target. There are so many mosquitos that the few you repel really makes no difference on the population.

surajt88

Right. That's what I wanted to know.

thorium1010

why do you think that such kind of bugs should exist. Do you think mosquitoe bites are harmless , how would the body react to such a bite. you should realize that the chemical released initiates a reaction in our body which we perceive as itching.

http://en.wikipedia.org/wiki/Insect_bites_and_stings

Moonbear

Mosquitoes don't get a choice in the matter. The only natural selection that matters is that they can breed faster than we can swat them. We actually help them by leaving around items that collect stagnant water where a lot of them can breed. But even if we decided to eradicate everything that made us itch, they can't just suddenly develop a new way of feeding on demand. That's not how evolution works.

DaveC426913

No but what might happen is a mosquitoes might evolve that is slightly less itchy to us, allowing more of them to survive and breed. 'course this wouldn't likely happen unless humans comprised the lion's share of their diet.

thorium1010

Was this referring to my post, if it is - i was not even talking about evolution. The OP was referring to itching which has less to do with evolution, than a simple chemical reaction that the body has to foreign substances. This occurs in variety of cases not just mosquito bites, also to to chemicals which we use daily.

Feeding is a different story, it can be achieved without producing the irritant substance (think leeches! ).They(Leeches) achieve by secreting a anticoagulant, can feed for days or months without even the host noticing.

http://en.wikipedia.org/wiki/Leech

256bits

Agree with the comment 'That is a very anthropocentric point of view.'

feathermoon

My sister, a year or two ago, mentioned to me a theory she read about: mosquitos don't evolve to be less annoying because it helps their species overall. The action of slapping at mosquitos brings more blood to the surface area where they feed on animals, and so even if a few members of the population die from it, as a whole they feed better.

Ryan_m_b

Actually mosquitoes also release an anticoagulant and as far as I'm aware leech bites itch after the fact too. The itching from a bite does not occur whilst one is being bitten but after and is due to an immune response against the secretions from the bite.

As for an evolutionary take on this first there is the question of if it would be a selective advantage as the mosquito has left before swelling and itching occurs. Also that the capability to evolve a means of evading the immune system may be nowhere near on the fitness landscape and may require many detrimental mutations before reaching that step therefore it is unlikely to occur.

Moonbear

And unlikely to happen at all unless there are already hypoallergenic mosqitoes around. They can't just acquire a trait that isn't in their population.

As others have pointed out, the itch is after the fact anyway. By the time you're itching, the mosquito is long gone.